Pelletisation process

Abstract

Pellets of iron ore or other water insoluble particulate material are made from a mixture of the particulate material, moisture and a pelletizing binder by forming moist green pellets, a water displacing additive is applied to the surface of these pellets after they are substantially wholly formed, and the pellets are then dried. The preferred water displacing additive is a solution of a silicone in an organic solvent.

We claim: 
     
       1. A process in which pellets of water insoluble particulate material are made by providing a mixture of the particulate material, moisture and a pelletising binder, forming moist green pellets by pelletising this mixture by a balling drum or disk pelletiser, applying a non-aqueous water displacing additive to the surface of the moist green pellets after they are substantially wholly formed and thereby displacing water from the surface of the pellets, and then drying the green pellets. 
     
     
       2. A process according to claim 1 in which the particulate water insoluble material is a mineral ore in which substantially all the particles are below 300 μm in size. 
     
     
       3. A process according to claim 1 in which the binder comprises a water soluble organic polymeric material or bentonite or a mixture thereof. 
     
     
       4. A process according to claim 1 in which the binder comprises a water soluble polymer of 5 to 30% acrylic acid with 95 to 70% acrylamide and having intrinsic viscosity of 3 to 15 dl/g alone or, mixed with bentonite. 
     
     
       5. A process according to claim 1 in which the binder also includes sodium carbonate. 
     
     
       6. A process according to claim 1 in which the pellets are made in a pelletising drum and the moisture displacing additive is applied to the pellets as they leave the drum or subsequently and the pellets are agitated after application of the moisture displacing additive. 
     
     
       7. A process according to claim 1 in which the water displacing additive is a material that reduces the critical surface tension of the surface of the pellets to a value that is lower than the surface tension of water. 
     
     
       8. A process according to claim 1 in which the water displacing additive is a lubricant for the pellets. 
     
     
       9. A process according to claim 1 in which the water displacing additive comprises an organic solvent or a silicone or a mixture thereof and contains less than 10% water. 
     
     
       10. A process according to claim 1 in which, after application of the water displacing additive, the pellets are dried at from 300 to 700° C. and are then fired at a temperature above 1000° C.